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SOUTHSIDE BANCSHARES , INC . ANNOUNCES FINANCIAL RESULTS FOR THE THIRD QUARTER ENDED SEPTEMBER 30 , 2021 Third quarter net income of $ 29.3 million ; • Third quarter earnings per diluted common share of $ 0.90 ; • Annualized linked quarter loan growth , net of Paycheck Protection Program ( “ PPP " ) loans , 7.9 % ; • Annualized linked quarter deposit growth of 13.5 % ; • Linked quarter net interest margin increased to 3.16 % ; • Annualized return on third quarter average assets of 1.61 % ; • Annualized return on third quarter average tangible common equity of 17.10 % ( ¹ ) ; and • Nonperforming assets decreased to 0.17 % of total assets . EXHIBIT 99.1 Tyler , Texas ( October 26 , 2021 ) Southside Bancshares , Inc. ( " Southside " or the " Company " ) ( NASDAQ : SBSI ) today reported its financial results for the quarter ended September 30 , 2021. Southside reported net income of $ 29.3 million for the three months ended September 30 , 2021 , an increase of $ 2.2 million , or 8.2 % , compared to $ 27.1 million for the same period in 2020. Earnings per diluted common share were $ 0.90 and $ 0.82 for the three months ended September 30 , 2021 and 2020 , respectively . The annualized return on average shareholders ' equity for the three months ended September 30 , 2021 and 2020 was 12.89 % . The annualized return on average assets was 1.61 % for the three months ended September 30 , 2021 , compared to 1.48 % for the same period in 2020 . " We reported outstanding third quarter financial results , highlighted by annualized linked quarter deposit and loan growth , net of PPP loans , of 13.5 % and 7.9 % , respectively , an increase in our net interest margin to 3.16 % , net income of $ 29.3 million and continued strong asset quality , " stated Lee R. Gibson , President and Chief Executive Officer of Southside . " These results could not have been achieved without the tremendous efforts and contributions of the entire Southside team and for this , I am extremely proud and grateful . " " On September 30 , 2021 , we redeemed our 5.5 % coupon $ 100 million subordinated notes due 2026 , which will have a positive impact on our net interest margin in the fourth quarter . We expensed $ 1.1 million during the third quarter in connection with the redemption of the subordinated notes . " " Our loan pipeline is strong , however , anticipated payoffs in the fourth quarter will generate some continued headwinds . We remain encouraged by the continued strong economic conditions in the market areas we serve . " Operating Results for the Three Months Ended September 30 , 2021 Net income was $ 29.3 million for the three months ended September 30 , 2021 , compared to $ 27.1 million for the same period in 2020 , an increase of $ 2.2 million , or 8.2 % . Earnings per diluted common share were $ 0.90 and $ 0.82 for the three months ended September 30 , 2021 and 2020 , respectively . The increase in net income was primarily a result of an increase in noninterest income and net interest income , partially offset by an increase in income tax expense . Annualized returns on average assets and average shareholders ' equity for the three months ended September 30 , 2021 were 1.61 % and 12.89 % , respectively , compared to 1.48 % and 12.89 , respectively , for the three months ended September 30 , 2020. Our efficiency ratio and tax equivalent efficiency ratio ( 1 ) were 50.64 % and 47.92 % , respectively , for the three months ended September 30 , 2021 , compared to 52.77 % and 50.07 % , respectively , for the three months ended September 30 , 2020 , and 53.09 % and 50.31 % , respectively , for the three months ended June 30 , 2021 . Net interest income for the three months ended September 30 , 2021 was $ 48.2 million , compared to $ 46.6 million for the same period in 2020 , an increase of 3.5 % . The increase in net interest income compared to the same period in 2020 was due to the decrease in interest expense on our interest bearing liabilities due to the overall decline in interest rates and a decline in the average balance of our interest bearing liabilities , partially offset by the decrease in interest income , a result of a decrease in the average balance of our interest earning assets during the three months ended September 30 , 2021. Linked quarter , net interest income increased $ 2.6 million , or 5.6 % , compared to $ 45.6 million during the three months ended June 30 , 2021. The increase in net interest income is primarily due to an increase in the average yield and balance on our interest earning assets . Page - 1